小螺桨烷中C—C中心键的量子化学研究

用MNDO半经验分子轨道理论对一系列小环螺桨烷[1.1.1]螺桨烷、[2.1.1]螺浆烷、[2.2.1]螺浆烷及[2.2.2]螺桨烷中的C—C中心键进行了研究.结果表明小螺桨烷的边键与一般环状分子的C—C键强度接近,而在中心C—C上则形成一种比正常环状分子稍弱的共价键;随着螺浆烷环的增大,其C—C中心键强度增大,计算结果与前人实验和理论研究的结论一致。

Quantum Chemical Study of the C-C Central Bonds in Small Propellanes

In this paper, using semiempirical molecular orbitals MNDO procedures, the central bonds in small propellanes, such as [1. 1. 1], [2. 1, 1], [2. 2.1], [2. 2. 2] propellanes, are studied. The calculation results show that the strength of the side bonds in small propellanes is close to that of the bonds in common ring molecules, while the weaker covalent bonds are formed between the bridgehead carbon atoms than the bonds in common ring molecules. As the size of the rings in propellanes increases, the strength of the C-C central bonds increases. Our theoretical calculations are in good agreement with the experimental and theoretical conclusions reported.